As energy consumption in the United States and throughout the world continues to increase, additional methods for environmentally clean energy conversion that can convert biomass, coal, or other solid or nonconventional heavy hydrocarbon energy resources to hydrogen, synthetic fuels and chemicals are desired. Concerns about the increased wastes and pollutants produced by many of the conventional energy conversion processes, and the low efficiencies of such processes, have led to further research for cleaner, more efficient processes.
In response to the increasing energy demands and the desire to reduce or eliminate pollutants, new cleaner, energy conversion processes that can utilize biomass, coal, or other solid or nonconventional heavy hydrocarbons are being sought. A known process for conversion of these energy resources to cleaner fuels includes synthetic fuels, often referred to as “synfuels,” which are made from synthesis gas, often referred to as “syngas.” Syngas includes a mixture of varying amounts of carbon monoxide (CO) and hydrogen (H2) that may be converted to form hydrogen, synfuels, methanol or chemicals. Production of synfuels from syngas may be performed using a variety of processes including a Fischer-Tropsch process to convert the carbon monoxide and hydrogen into liquid hydrocarbons as shown below in Reaction 1:(2n+1)H2+nCO→CnH(2n+2)+nH2O   (Reaction 1)
The synfuels produced using the Fischer-Tropsch process may include high purity, low sulfur, fuels, often referred to as “Fischer-Tropsch liquids,” which have fewer pollutants than naturally occurring fuels or fuels processed from naturally occurring oil deposits.
Another approach is to convert syngas into methanol, which may be converted to gasoline, olefins, or aromatics. Syngas may be converted to methanol using a copper or zinc catalyst such as a modified ZSM-5 catalyst.
High temperature solid-oxide fuel cells may be used to produce electricity and water from hydrogen and oxygen (O2). When run in reverse, the solid-oxide fuel cells are called solid-oxide electrolysis cells and are able to electrolytically reduce and split water into hydrogen and oxygen and carbon dioxide into carbon monoxide and oxygen. The water may be converted into hydrogen, which may be combined with carbon monoxide to form syngas. In a solid-oxide electrolysis cell, the anode is the reducing gas electrode and the cathode is the oxidant-side electrode. When operated in reverse, as a solid-oxide electrolysis cell, the anode is the oxidant-side electrode and the cathode is the reducing gas electrode. Furthermore the solid-oxide electrolysis cell may be used to co-electrolyze a mixture of water and carbon dioxide to produce syngas.
Improvements to systems and processes for producing syngas are continually sought after by various industries. It would be beneficial to develop efficient systems and methods of producing syngas while minimizing carbon emissions.